1. Field of the Invention
The present invention relates to pneumatic connectors for use with respiratory sensors, In particular, the present invention relates to pneumatic connectors for securing the ends of mutually laterally adjacent tubes to the ends of other tubes or to another structure. More particularly, the present invention relates to pneumatic connectors which include an indicator mechanism for determining the characteristics of a sensor associated with the tubes being connected to a monitor or other host device. The present invention also relates to pneumatic connectors which include mechanical keying mechanisms thereon.
2. Background of Related Art
Connectors for pneumatic tubing lines are well known. Typically, a pneumatic line connecter includes two coupling members, each attached to an end of a pneumatic tube to be mutually connected with their bores in communication to define a longer fluid line extending through both tubes. Connectors are also employed to connect one or more tubes to a device such as a monitor with transducer, processing, and/or display electronics for sensing, processing and/or displaying one or more parameters of a fluid in the tube or tubes, As the two members are adjoined, they connect the two tubes of a line with a airtight seal. Many such connector devices include hollow nipples, which are insertable into the tube ends, for attaching the tubing thereto. Many devices also employ an interference fit between rigid, mating elements of the two coupling members to provide a tight seal between the two coupling members. Some devices also include relatively complex mechanisms for maintaining the connection. U.S. Pat. No. 4,076,279 (the "'279 patent"), issued to Heinz Klotz and Dietmar Padszuck on Feb. 28, 1978, No. 5,197,895 (the "'895 patent"), issued to Josef J. Stupecky on Mar. 30, 1993, and No. 5,405,269 (the "'269 patent"), issued to Josef J. Stupecky on Apr. 11, 1995, disclose exemplary tubing connection devices. The device of the '279 patent is capable of connecting cooperating pluralities of tubes to form a longer plurality of lines. The device disclosed in both the '895 and '269 patents connects tubes to form one or more fluid lines and connects wires along one or more electrical lines.
Many tubing connectors are undesirable from the standpoint that they fail to maintain a uniform internal diameter along the entire line extending from tube-to-tube, or at a point of entry of a tube into a monitor or other host device. The insertion of nipples into the tubing alters (expands) the internal diameter of the tube at the connected end thereof. Moreover, the nipples of some connectors have a different internal diameter than the tubing attached thereto. Similarly, the use of an interference fit between elements of the two rigid members of a coupling device may also compress a bore of the coupling device and thus constrict a portion of the internal diameter of a connected line. Variation in a tubing line's internal diameter may be especially problematic in applications where flow and pressure are being measured, since abrupt variations may induce false readings of the flow rate and pressure of the sampled gases or other fluids. Further, the aforementioned types of coupling member-to-tube connection may induce significant variations in the relatively small total internal volume of the tubing line and associated devices.
Some coupling devices, such as that disclosed in the '279 patent, lack a mechanism for ensuring that each line connects only to its correct, corresponding line associated with the mating part of the coupling device. In applications where the characteristics of the transported fluid media differ, and where each line has a different destination, the lack of such a mechanism could have detrimental, if not catastrophic, results. For example, the direction of a respiratory gas content sample into a respiratory flow and/or pressure monitor could provide inaccurate flow and/or pressure data.
Many pneumatic connectors lack a mechanism for determining a type or characteristics of a sensor or sampling device associated with a tube or tubes being connected to another tube or tubes or to a monitor or other host device. This is undesirable when a plurality of devices of different structure or fabricated by different manufacturers, all suitable for use with a single monitor, are connectable thereto at the same sockets As those of skill in the relevant arts are aware, such different sensors may provide different air flow, pressure and other physical characteristic readings for the same patient if their characteristics are not "recognized" by the monitor. Stated another ways in order for a monitor to correctly assimilate a sample, it must make adjustments and/or calibrations specific to the type of sensor that was employed to collect the sample in question.
U.S. Pat. No. 5,660,567 (the "'567 patent"), issued to Steve L. Nierlich et al. on Aug. 26, 1997, discloses a connector for a medical sensor which includes an electronic device for encoding a characteristic of the sensor. The encoding device is a resistor which is matched to the specific sensor. Upon determining the type of sensor attached thereto, a monitoring device makes appropriate adjustments to correctly accommodate the output from the sensor However, the sensor type encoding system of the '567 patent is undesirable for several reasons. First, the addition of a resistor for encoding the device type requires at least one additional component as well as an additional manufacturing step in the assembly of each member of the connector. Second, the use of such a resistor requires the alignment of two additional (electric) lines during coupling Third, the resistor contacts are prone to being bent, broken, or otherwise damaged during coupling of the two connector members.
What is needed is a pneumatic connector assembly which includes a reliable, compact, low-cost; easy-to-use mechanism for accurately identifying the type of sensor attached thereto. There is also a need for a pneumatic connection or assembly which maintains a uniform internal diameter along each tubing-connector-tubing line, and which provides and maintains a good seal at relatively high respiratory sampling pressures. Such A device is also needed specifically to connect a plurality of mutually adjacent pneumatic tubes to another plurality of tubes or to the input of a monitor. A pneumatic connector assembly is also needed which includes a mechanical keying mechanism to ensure that only appropriate devices are connected, and that proper "polarity" (i.e., the correct opposing tubing bores are mated) is effected by the connection.